yea it calls player interface, i dont really know which mods are adding it, but i know there a 2 variants from two mods. Maby just search for it in nei.
Yea i have the same error, i think the download server are in maintenance, stick to the current version of the ftb launcher you have installed, it right way starts when you dismiss the error alert!
It can often be very annoying when the server crashes and then won't start anymore.
Therefore I show you how to use the restart script and how to adapt it to your needs
First at all create a file with the name like start.sh with the following content:
#!/bin/bash
echo "Restart Script"
while ...